MAES Pilot: Utrecht is growing greener

Transcription

1 MAES Pilot: Utrecht is growing greener 12 February 2016 Authors: Municipality of Utrecht Alterra Hans Kruse (ecology advisor) Albert de Vries (consultant subsurface & natural capital) Michiel van Eupen Marta Pérez-Soba Peter Verweij From concepts to real-world applications

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3 3 Table of content 1. Policy context Mapping urban ecosystems Mapping ecosystem condition Mapping urban ecosystem services Conclusions

4 4 1. Policy context Text extracted and adapted from Green Surge Report of city portraits (2015) Introduction Utrecht is the fourth largest city of the Netherlands. It is a transport hub with highways, rivers and railways passing or transecting the city, which entail one of the biggest spatial challenges. Its central location makes the city attractive for commuters, as it is shown by the fact that Utrecht is growing faster than the other largest cities in the Netherlands (Amsterdam, Rotterdam and The Hague). The population size is 335,000 in 2015 and is expected to grow to in Utrecht is home to one of the largest universities of the Netherlands and the population is relatively young and highly educated. The city is also famous for its historical centre with inner-city canals, wharfs and protected trees as significant infrastructure (see figure 1). Figure 1: Historical centre of Utrecht The national task to expand available housing has been particularly dominant in changing the city. Through the new housing development of Leidsche Rijn, Utrecht is expected to grow by 100,000 inhabitants, 30,000 houses, 770,000 m 2 of commercial office space, and 230 hectares of business area by This is the largest in scale of the housing programmes in the Netherlands that have been implemented over the past few decades. In addition, space for green infrastructure is often limited due too high paved and built surfaces. For example, the large scale redevelopment project of the station area (see figure 2), where next to the highly built surfaces also high demands for new grey infrastructure are present. At the same time Utrecht has the ambition to become a sustainable, green and healthy city. How to realize this ambition with green and blue solutions is a great challenge, because in practice green and blue spaces appear to be the weak element in the final decision making process. The concept of Ecosystem Services may help to strengthen the value of green and blue solutions. 4

5 5 Figure 2: schematic situation of water system in station area of Utrecht Green Urban Planning in Utrecht The main instrument for the protection and enhancement of urban green space in Utrecht is the Urban Green Structure Plan of 2007 (see figure 3). The Green Structure Plan distinguishes green around the city, green structures in the city, and green in the city. It is connected with multi-annual green programs that elaborate in greater detail which measures are to be taken in view of the agreed priorities, how these measures will be financed and a planning schedule. The program emphasizes how cooperation with actors such as the province, the municipal land exploitation, the national government and the EU is important for realizing investments in the green structure. The multi-annual green program is updated on a yearly basis. A second important instrument for the protection and enhancement of green space is the Utrecht Trees policy of The policy emphasizes that trees have got their own spatial dimension and problems that merit a special policy document including components such as tree structure, instruments, and guidelines for the management and maintenance of trees. Figure 3: Green structure plan of Utrecht Apart from these instruments there is since 2009 a subsidy regulation for the construction of green roofs. At a neighbourhood level, ten neighbourhood plans were made with green ideas and proposals of inhabitants and budget was provided by the municipality to realize most of the proposals. 5

6 6 Ecosystem services In cities like Utrecht, we are used to look at different (technical) measures, indicators and solutions from separated themes and departments. With an ecosystem service framework and the use of green infrastructure, Utrecht aims to improve a healthy urban living by an integrated and new approach. To initiate this process better, the project green agenda Maarschalkerweerd has been started in The project is aimed at strengthening the green qualities and benefits that ecosystem services deliver to an urban areas on district level. Hence, the emphasis lies on a partnership with residents, users and stakeholders to analyse the natural capital in the area and to identify opportunities and threats in terms of implementing the green qualities and ecosystem services of the area. The assessment of ecosystem services was made based on expert judgement, as maps of urban ecosystems were not directly available. 2. Mapping urban ecosystems The data sources used to map green urban ecosystems in Utrecht for the MAES pilot project are listed in Table 1. Table 1: Data sources to map green urban infrastructure in MAES pilot Name Source Reference Green Structure Plan 2030 Trees & Green Management maps Utrecht municipality Utrecht municipality Trees structure maps Alterra & Utrecht municipality Neighbourhood green plans (10 districts) CBS & Kadaster 2016 opendata@utrecht.nl opendata@utrecht.nl Processed at 2.5 m raster level from Air quality maps RIVM PM10 b472 d8ac-2eb0-4a79-96fc-f0cbc1f717bb Noise maps Noise from Road & Train Heat stress maps USGS Present reflectance temperature [Degrees Celsius] (July 15, 2015), LANDSAT 8 band 10 & 11, converted to o C Land cover maps Alterra TOPNature: Scaleless-enriched 2.5 m raster version of TOP10NL for fast web mapping visualization and ecological applications Buildings in the Netherlands Kadaster Basisregistraties Adressen en Gebouwen (BAG) 6

7 7 All data were rasterized at a resolution of 10x10 meters and put into the QUICKScan tool with the appropriate legend and classification. 3. Mapping ecosystem condition At this moment the city of Utrecht has no structural working method to gather data and information to broadly assess the ecosystem condition in the city. However, useful information is available at district and city scales, as those mentioned in Table 1. In addition: - Recreational maps; - Groundwater network data and maps; - Land Cover maps; - Soil quality maps. 4. Mapping urban ecosystem services Experts from the Municipality of Utrecht, in collaboration with researchers from Alterra identified a set of key ecosystem services relevant for the city: local climate regulation, noise reduction, recreation, and cleaner air. In two workshops, they developed maps of the current potential supply of the four key ecosystem services for each of the city districts. In addition, they developed maps for different scenarios to make Utrecht greener: - greening the noisy impervious areas combined with adding green roofs - allowing current trees grow older (2050) to develop more dense crown coverage - add green areas with minimum 20% crown coverage in urban restructuring areas Figure 4 shows the maps and graphs developed for climate regulation and noise reduction. It shows the present reflectance temperature per land use class [Degrees Celsius] (July 15, 2015). Buildings, squares and flat roofs are among the hottest areas in the city, with flat roofs clearly topping the scales. Road(sides) and other green areas show already a 1-2 degree Celsius lower temperature. Grasslands and forest inside the main city area are up to 3-4 degrees cooler than flat roofs. ). In addition, it shows the average temperature in the different neighbourhoods of Utrecht under the three scenarios compared with the present situation. The more agricultural neighbourhood of Vleuten-de Meern shows considerably lower temperatures, and the city centre ( Binnenstad ) on average the highest. The maximum average effect at neighbourhood level is about half a degree Celsius in the given scenarios, locally much larger effects are visible in the maps. Letting the tree crowns grow to 2050 in general give the best reduction. The magnitude of the effect of more trees in the restructuring areas or green roofs and greener noisy areas is depending on the neighbourhood. Figure 5 shows the maps developed for recreation. The starting point was the Green structure plan of Utrecht, with green nodes connected by green infrastructure. The size of the node was used as proxy for the recreation potential/capacity. Two distances were calculated: 1) Travel distance to any green node; and 2.) Only the major (larger) nodes. Recreational potential of land cover in and around Utrecht was based on expert knowledge rules. It showed that the city centre ( Binnenstad ) has a very limited green recreational potential. Neighbourhoods further away from the city centre ( Vleuten, Overvecht and Oost ) have more potential, this is in line with the areas and major nodes as defined in the Green structure plan of 7

8 8 Utrecht. The analysis of the recreation potential considering the Green structure plan of Utrecht, showed that in the plan the travel distance to one of the green nodes is equally dispersed over the city. The only exception is for the inhabitants of the city centre ( Binnenstad ) that have to travel 900 m to reach one of the nodes. If considering only the major/larger nodes, the differences between the neighbourhoods become much more extreme with distances up to 2 kilometres for people in West. They are (relatively) isolated by the canals and a limited amount of bridges, causing extra travel distance to the major recreational nodes. Figure 6 shows the maps developed for air purification capacity based on the relation between tree crown coverage percentage and land cover type, the denser the tree crown is the better the purification of the air (PM10). Since all area in the city is within legal environmental limit, but still on a relative high level, no spatial distinction is made where to apply the measures. Scenarios developed for temperature reduction were applied to air purification to show the additive effect. Differences between the scenarios result all in an improvement of the present situation. The scenario with the highest capacity is increasing tree crown coverage by letting them grow until The scenario green roofs & greening noisy impervious areas shows the highest overall effect over the study area. 8

9 MAES Pilot Report- Utrecht is growing greener 9 Present reflectance temperature per land use class [Degrees Celsius] (July 15, 2015) Buildings, squares and flat roofs are among the hottest areas in the city, with flat roofs ( Platte daken ) clearly topping the scales. Road(sides) and other green areas show already a 1-2 degree Celsius lower temperature (Yellow arrows). Grasslands and forest inside the main city area are up to 3-4 degrees cooler than flat roofs (green arrows). Reflectance temperature Landsat 8. Celsius Current land use Scenario let trees grow older (2050) to develop more dense crown coverage Current temperature Scenario add green areas with min. 20% crown coverage in urban restructuring areas Land Use Tree crown coverage (%) Reflectance temperature Landsat 8. Celsius Tree crown coverage (%) Scenario greening the noisy impervious areas combined with... greening flat roofs Temperature reduction (degree Celsius) Temperature reduction (degree Celsius) Average temperature in the different neighbourhoods of Utrecht under the three scenarios compared with the present situation (yellow). The more agricultural neighbourhood of Vleuten-de Meern shows considerably lower temperatures, and the city centre ( Binnenstad ) on average the highest. The maximum average effect at neighbourhood level is about half a degree Celsius in the given scenarios, locally much larger effects are visible in the maps. Letting the tree crowns grow to 2050 in general give the best reduction. The magnitude of the effect of more trees in the restructuring areas or green roofs and greener noisy areas is depending on the neighbourhood. 9

10 10 Acessibillity to any green node in the 2008 green structure plan of Utrecht Distance to major green nodes in the 2008 green structure plan of Utrecht Green structure plan of Utrecht, with green nodes connected by green infrastructure. The size of the node was used as proxy for the recreation potential/capacity. Two distances were calculated: 1) Travel distance to any green node; and 2.) Only the major (larger) nodes Recreational potential of land cover in and around Utrecht based on expert knowledge rules, show that the city centre ( Binnenstad ) has a very limited green recreational potential. Neighbourhoods further away from the city centre ( Vleuten, Overvecht and Oost ) have more potential, this is in line with the areas and major nodes as defined in the Green structure plan of Utrecht The analysis of the recreation potential and the Green structure plan of Utrecht shows that in the plan the travel distance to one of the green nodes is equally dispersed over the city. Only the inhabitants of the city centre ( Binnenstad ) have to travel 900m to one of the nodes. When taking into account only the major/larger nodes the differences between the neighbourhoods become much more extreme with distances up to2 kilometres for people in West. They are (relatively) isolated by the canals and a limited amount of bridges, causing extra travel distance to the major recreational nodes 10

11 11 Air purification capacity based on the relation between tree crown coverage percentage and land cover type, the denser the tree crown is the better the purification of the air (PM10). Since all area in the city is within legal environmental limit, but still on a relative high level, no spatial distinction is made where to apply the measures. Scenarios developed for temperature reduction were applied to air purification to show the addition effect Differences between the scenarios result all in an improvement of the present situation. The scenario with the highest capacity in the top category (red) is increase of tree crown coverage by letting them grow to The scenario green roofs & greening noisy impervious areas shows the highest overall effect over the study area. Relation between tree crown coverage percentage and land cover type, the denser the tree crown is the better the purification of the air (PM10). Deciduous forest purifies less than needle leaved forest. Other land cover classes just have a mediocre purifying capacity Overall differences between the scenarios average over the total study area of the Municipality of Utrecht 11

12 12 5. Conclusions The analysis of the current situation of green services and its comparison with the results of three different greening scenarios in Utrecht, help to understand the impact of green areas on human well- being, i.e. lower temperatures in hot summer days, less noise, lower distances to green areas. The benefits and their value cannot be derived directly from the results, as more processing and calculating is needed based on estimations, since direct relation to human well-being benefits is still limited. The sum of potential benefits from these ecosystem services may give an indication. In addition the monetary valuation of all benefits can be useful for stakeholders involved in re-developments in the Utrecht area. The maps and graphs developed with the QUICKScan give a good overview of the ecosystem services being present at district scale and total city scale and help to compare the impact of different green management alternatives. For example, the present temperatures per land use class show a significant and maximum difference of temperature of 4 degrees for Utrecht corresponding to land use type grass (lowest) and flat roofs (highest). Also the distinction between flat roofs and other roof types gives a small difference of 1 degree. As regards potential climate adaptation measures for Utrecht: increasing the tree crown coverage has higher impact than adding green roofs on flat roofs. The positive effect of an increase of tree crown density is partly due to planting extra trees. This will also result in a potential benefit for the ES service water storage capacity of the open soils underneath and around these trees. As storage of water in soils also contribute to the filtration and transformation of nutrients and contamination from storm water runoff. This quick scanner of opportunities support the inclusion of these two ES in a follow up exercise, where these services will be quantified based upon scientific knowledge. How the different ecosystems actually function could be a follow-up exercise towards more knowledgebased measures in urban practice. According to Utrecht experts, the maps and data can also be very useful as a communication tool. Overall the maps and quick assessment of these ecosystem services provide a useful starting point to support Utrecht s policy to reach a healthy urban living, and its implementation in daily urban practice. 12